Stage 1 — Incoming inspection (Day 1–2)
Verify the sample matches the RFQ spec before any further testing. Reject early if geometry or bond type is wrong.
- Dimension check Width, thickness, diameter, camber — 10 samples, Cpk ≥1.33
- Bond type verification Cross-section microscope — confirm metallurgical cladding, not electroplating
- Visual and surface No scratches, oxide stains, coating skips >5% of surface
- Spool and packaging Match automation equipment; no deformation, no splice in 200 m
Stage 2 — Material and electrical (Day 3–7)
Confirm the conductor meets electrical and mechanical targets in the as-delivered state, before process integration.
- Conductivity % IACS via resistance bridge, 3 samples, ±2% of spec
- Tensile and elongation ASTM B566 for CCA; record yield and break strength
- Bond strength Peel test or shear test — ≥60 MPa for CCA, ≥80 MPa for NCC
- Coating thickness XRF, 5 points per sample, within ±10% of spec
Stage 3 — Process integration (Day 8–18)
Run the sample through the actual production process: stamping, welding, soldering, bending. Capture process parameters and yield.
- Solderability (PV / harness) Wetting balance test, zero-cross time <2 s
- Stamping and forming (terminals) No cracking at bend radius; burr <10% of thickness
- Welding (busbar / battery) Pull strength ≥spec; no voids in cross-section
- Process yield Run 500 pieces, yield ≥98% before pilot approval
Stage 4 — Reliability (Day 19–30)
Run accelerated life tests that match the end application. Failures here disqualify the sample from PPAP.
- Thermal cycling PV: TC200; EV: TC1000 per USCAR-38
- Damp heat PV: DH1000; general: 85°C/85%RH 500 h
- Vibration (EV / aerospace) Random vibration per ISO 16750 or application spec
- Post-test inspection No delamination, no resistance increase >5%, no visible cracks
Common failure modes and what they mean
If a sample fails, use this table to identify the root cause category before contacting the supplier.
| Failure | Likely root cause | Action |
|---|---|---|
| Peel strength low | Insufficient cladding ratio or weak bond | Request cross-section + bond strength report |
| Resistance high | Cladding ratio below spec or temper wrong | Re-check % IACS and alloy cert |
| Cracking at bend | Temper too hard or cladding too thin | Request softer temper or thicker cladding |
| Solderability fail | Coating oxidized or wrong alloy | Request coating thickness + wetting test |
| Delamination after TC | Bond not metallurgical (electroplated) | Reject supplier — bond type mismatch |